361] ANOPLOCEPHALIDJE—DOUTHITT 11 



dorsoventral diameter in the center is 225/*. The transverse commissure 

 measures at its largest point about 100/*; at either end it becomes 

 smaller. As the proglottids age the ducts keep on increasing in size. 

 The largest dimensions observed for the transverse commissure were 

 320/*.; for longitudinal ducts, exclusive of interproglottidal enlarge- 

 ments, both transverse and dorsoventral diameters reached 320/*; for 

 interproglottidal enlargements, 430/*. As the proglottids lengthen prior 

 to detachment, the ducts become smaller as the result of the stretching, 

 and the interproglottidal enlargements which are not thus affected be- 

 come prominent as spindle-shaped objects. 



Since the maximum breadth of this worm is 1.5 mm. it will be seen 

 that this development is truly enormous, the two ventral ducts extend- 

 ing in some cases through not far from one half the transverse measure- 

 ment of the proglottid and dorsoventrally through the cortical layer. 

 This is not due to reagents since the living worms exhibit the enormous 

 ducts clearly visible to the naked eye, before being given any treatment 

 whatever. Great as this development is however it will be seen that it 

 is exceeded in An dry a translucida, the next form to be considered, tho 

 with the difference that in the present species the dimensions are con- 

 stant in any given stage of development of the proglottid while in the 

 other they will suddenly develop enormously and then as suddenly 

 decline. These enormous ducts make these two species quite transparent 

 in life. 



The cestode is contractile when alive ; it is from 10 to 20 cm. long 

 and is composed of from 345 to 455 proglottids, the average of 14 

 specimens being 393. In well expanded specimens the neck is 1.5 mm. 

 long, in one case even 3 mm. while in some contracted specimens it is 

 only 0.3 mm. The diameter varies from 0.2 to 0.6 mm. The strobila 

 increases in width gradually to reach the maximum width of 1.5 mm. 

 about one-third of its length from the anterior end. From this point 

 back the width remains about constant. Sexually mature proglottids, 

 which begin about the 145th in the strobila, measure in a typical speci- 

 men 0.3 mm. long by 0.9 mm. broad. 



The very large scolex is nearly globular in form, being 600 to 800/* 

 wide and 700 to 950/* long; eleven specimens which were measured 

 averaged 709/* wide by 811/* long. One finds but slight indications of 

 grooves between the suckers ; the very shallow depressions fade out 

 before reaching the apex. The suckers are very large, thin-walled 

 structures, usually collapsed and opening directly forwards. Their 

 diameter is 300/* and their depth, 415/*. Their muscular wall is 50/* 

 thick and the orifice is 50/* across. 



